Conventionally, an automatic color change paint spray system for vehicle bodies moving on a mass production line is generally composed of a spray nozzle or gun mounted on a travelling carriage and a plurality of color change valves mounted near the carriage connected to sources of paint by suitable hoses. The distance from the valves to the spray nozzle is about 4 to 5 meters. The valves are connected with the spray nozzle by a common manifold and a single hose. A thinner and air supplying valve unit is associated with the valves such that cleaning for a color change is carried out by cleaning the manifold and single hose connecting the manifold with the spray nozzle first by flushing with thinner or solvent and then drying with air. The automatic color change paint spray system is controlled by orders from a control unit. In use, the automatic color change paint spray system supplies a selected colored paint to the paint spray nozzle or gun by way of the single paint feed tube leading from the manifold to the spray gun. Japanese Patent Publication (Tokkosho) No. 59-50389 and other prior art discloses examples of such systems.
Although this known prior art system is generally satisfactory, its main drawback is that the distance from the paint color change valves to the spray gun is relatively long and due to the large number of paint colors for the vehicle painting that are presently required, diversification and the public's desire for more available colors, color change of successive vehicle bodies on the production line is more likely. Therefore, cleaning of the system for a color change occurs more frequently resulting in loss of paint and use of more solvent, air and power all of which result in a concomitant increase in cost.